[Migrated] Using `arch::ignore_intersection` causes shader compilation to fail

Issue automatically imported from old repo: https://github.com/EmbarkStudios/rust-gpu/issues/1099
Old labels: t: bug
Originally creatd by Steelbirdy on 2023-11-13T21:07:54Z

Expected Behaviour

Shader crate successfully compiles

Example & Steps To Reproduce

#[spirv(any_hit)]
pub fn my_any_hit() {
    let p = Vec3A::ZERO;
    if p.length_squared() < 1e-3 {
        unsafe { spirv_std::arch::ignore_intersection(); }
    }
}

1. Use the above snippet in a shader crate
2. Compilation fails

Replacing this with the below snippet causes it to compile.

#[spirv(any_hit)]
pub fn my_any_hit() {
    let p = Vec3A::ZERO;
    if p.length_squared() < 1e-3 {
        my_ignore_intersection();
    }
}

#[inline(never)]
fn my_ignore_intersection() {
    unsafe { spirv_std::arch::ignore_intersection(); }
}

System Info

• Rust: 1.71.0-nightly (1a5f8bce7 2023-05-26)
• OS: Windows 11
• GPU: NVIDIA RTX 3060 Ti

Backtrace

  error: Selection must be structured
           OpBranchConditional %1274 %1275 %1276
    |
    = note: module `C:\Users\Pat\CLionProjects\rayven_gpu2\target\spirv-builder\spirv-unknown-vulkan1.2\release\deps\shader.spv`

  warning: an unknown error occurred
    |
    = note: spirv-opt failed, leaving as unoptimized
    = note: module `C:\Users\Pat\CLionProjects\rayven_gpu2\target\spirv-builder\spirv-unknown-vulkan1.2\release\deps\shader.spv`

  error: error:0:0 - Selection must be structured
           OpBranchConditional %1274 %1275 %1276
    |
    = note: spirv-val failed
    = note: module `C:\Users\Pat\CLionProjects\rayven_gpu2\target\spirv-builder\spirv-unknown-vulkan1.2\release\deps\shader.spv`

提供された any-hit shader snippet でまず失敗を再現し、ヘルパー関数を使うバリアントと比較します。報告された OpBranchConditional の周辺にある生成済み SPIR-V を調べ、spirv-opt と spirv-val を使用して、ignore_intersection の直接呼び出しがなぜ非構造化された選択を生成するのかを特定します。元の snippet がコンパイルされ、SPIR-V の検証に合格すれば完了です。